/*
 * Created on Dec 4, 2004
 * Created by Alon Rohter
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package com.aelitis.azureus.core.networkmanager.impl.tcp;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.AsynchronousCloseException;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;

import org.gudy.azureus2.core3.logging.LogAlert;
import org.gudy.azureus2.core3.logging.LogEvent;
import org.gudy.azureus2.core3.logging.LogIDs;
import org.gudy.azureus2.core3.logging.Logger;
import org.gudy.azureus2.core3.util.AEMonitor;
import org.gudy.azureus2.core3.util.AEThread;
import org.gudy.azureus2.core3.util.Debug;
import org.gudy.azureus2.core3.util.SystemTime;

import com.aelitis.azureus.core.networkmanager.VirtualServerChannelSelector;

/**
 * Virtual server socket channel for listening and accepting incoming connections.
 */
public class VirtualBlockingServerChannelSelector implements VirtualServerChannelSelector {
    private static final LogIDs LOGID = LogIDs.NWMAN;
    private ServerSocketChannel server_channel = null;
    private final InetSocketAddress bind_address;
    private final int receive_buffer_size;
    private final SelectListener listener;

    protected AEMonitor this_mon = new AEMonitor("VirtualServerChannelSelector");

    private long last_accept_time;

    /**
     * Create a new server listening on the given address and reporting to the given listener.
     * 
     * @param bind_address
     *            ip+port to listen on
     * @param so_rcvbuf_size
     *            new socket receive buffer size
     * @param listener
     *            to notify of incoming connections
     */
    public VirtualBlockingServerChannelSelector(InetSocketAddress _bind_address, int so_rcvbuf_size, SelectListener listener) {
        this.bind_address = _bind_address;
        this.receive_buffer_size = so_rcvbuf_size;
        this.listener = listener;
    }

    /**
     * Start the server and begin accepting incoming connections.
     * 
     */
    public void start() {
        try {
            this_mon.enter();

            if (!isRunning()) {
                try {
                    server_channel = ServerSocketChannel.open();

                    server_channel.socket().setReuseAddress(true);
                    if (receive_buffer_size > 0)
                        server_channel.socket().setReceiveBufferSize(receive_buffer_size);

                    server_channel.socket().bind(bind_address, 1024);

                    if (Logger.isEnabled())
                        Logger.log(new LogEvent(LOGID, "TCP incoming server socket " + bind_address));

                    AEThread accept_thread = new AEThread("VServerSelector:port" + bind_address.getPort()) {
                        public void runSupport() {
                            accept_loop();
                        }
                    };
                    accept_thread.setDaemon(true);
                    accept_thread.start();
                } catch (Throwable t) {
                    Debug.out(t);
                    Logger.log(new LogAlert(LogAlert.UNREPEATABLE, "ERROR, unable to bind TCP incoming server socket to " + bind_address.getPort(),
                            t));
                }

                last_accept_time = SystemTime.getCurrentTime(); // init to now
            }
        } finally {

            this_mon.exit();
        }
    }

    /**
     * Stop the server.
     */
    public void stop() {
        try {
            this_mon.enter();

            if (server_channel != null) {
                try {
                    server_channel.close();
                    server_channel = null;
                } catch (Throwable t) {
                    Debug.out(t);
                }
            }
        } finally {

            this_mon.exit();
        }
    }

    protected void accept_loop() {
        while (isRunning()) {
            try {
                SocketChannel client_channel = server_channel.accept();
                last_accept_time = SystemTime.getCurrentTime();
                try {
                    client_channel.configureBlocking(false);
                } catch (IOException e) {
                    client_channel.close();
                    throw (e);
                }
                listener.newConnectionAccepted(server_channel, client_channel);
            } catch (AsynchronousCloseException e) {
                /* is thrown when stop() is called */
            } catch (Throwable t) {
                Debug.out(t);
                try {
                    Thread.sleep(500);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

        }
    }

    /**
     * Is this selector actively running
     * 
     * @return true if enabled, false if not running
     */
    public boolean isRunning() {
        if (server_channel != null && server_channel.isOpen())
            return true;
        return false;
    }

    public InetAddress getBoundToAddress() {
        if (server_channel != null) {
            return server_channel.socket().getInetAddress();
        }
        return null;
    }

    public long getTimeOfLastAccept() {
        return last_accept_time;
    }
}
